Report EISDIR when opening a directory on AIX

[azhan92]

Summary

Created by mistake, please refer here: https://reviews.llvm.org/D151567

[aaron.ballman]

Please add comments to the patch description explaining what's changing and why (this helps reviewers as well as during code archeology after the changes land).

llvm/lib/Support/Unix/Path.inc

17

Please do not include iostream: https://llvm.org/docs/CodingStandards.html#include-iostream-is-forbidden

1017–1024

This introduces a TOCTOU issue with the code -- there's now a window where stat will return the status of the file but that status can change before the call to open.

[azhan92]

Check if file is directory before opening for read.

[MaskRay]

llvm/lib/Support/Unix/Path.inc

1017–1024

I think non-AIX non-MVS systems don't want to introduce this behavior (TOCTOU).

[hubert.reinterpretcast]

llvm/lib/Support/Unix/Path.inc

1017–1024

Presumably the open call can be made first and fstat can then be used.

llvm/lib/Support/Unix/Path.inc

 //===- llvm/Support/Unix/Path.inc - Unix Path Implementation ----*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Unix specific implementation of the Path API.
 //
 //===----------------------------------------------------------------------===//
 
 //===----------------------------------------------------------------------===//
 //=== WARNING: Implementation here must contain only generic UNIX code that
 //===          is guaranteed to work on *all* UNIX variants.
 //===----------------------------------------------------------------------===//
 
 #include "Unix.h"
 #include <limits.h>
 #include <stdio.h>
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
 #if HAVE_FCNTL_H
 #include <fcntl.h>

 
 std::error_code openFile(const Twine &Name, int &ResultFD,
                          CreationDisposition Disp, FileAccess Access,
                          OpenFlags Flags, unsigned Mode) {
   int OpenFlags = nativeOpenFlags(Disp, Flags, Access);
 
   SmallString<128> Storage;
   StringRef P = Name.toNullTerminatedStringRef(Storage);
+  
+  if (Access == FA_Read) {
+    struct stat Status;
+    if (stat(P.begin(), &Status) == -1) 
+      return std::error_code(errno, std::generic_category());
+    if (S_ISDIR(Status.st_mode))
+      return make_error_code(errc::is_a_directory);
+  }
+
   // Call ::open in a lambda to avoid overload resolution in RetryAfterSignal
   // when open is overloaded, such as in Bionic.
   auto Open = [&]() { return ::open(P.begin(), OpenFlags, Mode); };
   if ((ResultFD = sys::RetryAfterSignal(-1, Open)) < 0)
     return std::error_code(errno, std::generic_category());
 #ifndef O_CLOEXEC
   if (!(Flags & OF_ChildInherit)) {
     int r = fcntl(ResultFD, F_SETFD, FD_CLOEXEC);

llvm/test/tools/llvm-symbolizer/input-file-err.test

-Failing on AIX due to D153595. The test expects a different error message from the one given on AIX.
-XFAIL: target={{.*}}-aix{{.*}}
 RUN: not llvm-addr2line -e %p/Inputs/nonexistent 0x12 2>&1 | FileCheck %s --check-prefix=CHECK-NONEXISTENT-A2L -DMSG=%errc_ENOENT
 RUN: not llvm-addr2line -e %p/Inputs/nonexistent 2>&1 | FileCheck %s --check-prefix=CHECK-NONEXISTENT-A2L -DMSG=%errc_ENOENT
 CHECK-NONEXISTENT-A2L: llvm-addr2line{{.*}}: error: '{{.*}}Inputs/nonexistent': [[MSG]]
 
 RUN: not llvm-symbolizer -e %p/Inputs/nonexistent 0x12 2>&1 | FileCheck %s --check-prefix=CHECK-NONEXISTENT -DMSG=%errc_ENOENT
 RUN: not llvm-symbolizer -e %p/Inputs/nonexistent 2>&1 | FileCheck %s --check-prefix=CHECK-NONEXISTENT -DMSG=%errc_ENOENT
 CHECK-NONEXISTENT: llvm-symbolizer{{.*}}: error: '{{.*}}Inputs/nonexistent': [[MSG]]
 
 RUN: not llvm-addr2line -e %p/Inputs 0x12 2>&1 | FileCheck %s --check-prefix=CHECK-DIRECTORY-A2L -DMSG=%errc_EISDIR
 RUN: not llvm-addr2line -e %p/Inputs 2>&1 | FileCheck %s --check-prefix=CHECK-DIRECTORY-A2L -DMSG=%errc_EISDIR
 CHECK-DIRECTORY-A2L: llvm-addr2line{{.*}}: error: '{{.*}}Inputs': [[MSG]]
 
 RUN: not llvm-symbolizer -e %p/Inputs 0x12 2>&1 | FileCheck %s --check-prefix=CHECK-DIRECTORY -DMSG=%errc_EISDIR
 RUN: not llvm-symbolizer -e %p/Inputs 2>&1 | FileCheck %s --check-prefix=CHECK-DIRECTORY -DMSG=%errc_EISDIR
 CHECK-DIRECTORY: llvm-symbolizer{{.*}}: error: '{{.*}}Inputs': [[MSG]]

llvm/unittests/Support/CommandLineTest.cpp

TEST(CommandLineTest, BadResponseFile) {
   SmallVector<const char *, 2> Argv = {"clang", AFileExp.c_str()};
 
   bool Res = cl::ExpandResponseFiles(Saver, cl::TokenizeGNUCommandLine, Argv);
   ASSERT_TRUE(Res);
   ASSERT_EQ(2U, Argv.size());
   ASSERT_STREQ(Argv[0], "clang");
   ASSERT_STREQ(Argv[1], AFileExp.c_str());
 
-#if !defined(_AIX) && !defined(__MVS__)
   std::string ADirExp = std::string("@") + std::string(ADir.path());
   Argv = {"clang", ADirExp.c_str()};
   Res = cl::ExpandResponseFiles(Saver, cl::TokenizeGNUCommandLine, Argv);
   ASSERT_FALSE(Res);
   ASSERT_EQ(2U, Argv.size());
   ASSERT_STREQ(Argv[0], "clang");
   ASSERT_STREQ(Argv[1], ADirExp.c_str());
-#endif
 }
 
 TEST(CommandLineTest, SetDefaultValue) {
   cl::ResetCommandLineParser();
 
   StackOption<std::string> Opt1("opt1", cl::init("true"));
   StackOption<bool> Opt2("opt2", cl::init(true));
   cl::alias Alias("alias", llvm::cl::aliasopt(Opt2));